Built on acoustics know-how, the sensor is coming in January for US$200

If you're looking to improve your tennis game through swing analysis, Sony is bringing its tennis racket sensor to the U.S. and Canada for about US$200.

The coin-size device, which fits into the handle of a racket, helps measure a number of swing variables and displays the data on a mobile device. It will be available from the end of January in partnership with racket makers Wilson, Prince and Yonex, the electronics giant said Thursday.

"We've had some feedback from users who were able to improve, for instance, their backhand or where the ball hits the racket," Yoshihiro Nakanishi, a user experience planner at Sony, said in an interview at the firm's Tokyo headquarters.

The sensor weighs about 8 grams and measures 31.33 millimeters in diameter, fitting into an attachment that goes in the pop-off cap area at the base of a racket's handle. Its rechargeable battery lasts about three hours if it's not tethered to a device.

It can connect via Bluetooth with smartphones and tablets to display swing stats on an associated app, available for iOS and Android devices.

The app can show real-time swing visualizations and metrics such as swing speed and ball spin as well as a map of the ball impact spot on the racket. There's a social media sharing function too.

The system can also distinguish between various kinds of swing, including a backhand slice, forehand with topspin, attack-style serve and smash.

It's able to do this because the sensor detects vibrations in addition to the speed and position of the racket. An algorithm that analyzes those vibrations draws upon Sony's decades of research into the physics of sound.

"Sound is a wave through air and vibration is a wave through a solid, and they are basically the same," Kosei Yamashita, senior sound engineer at Sony's system R&D group, wrote in an email.

"Thus, we were able to achieve highly accurate shot analysis using Sony's knowledge of music acoustic analysis techniques that it has developed up to now."

Sony's Smart Tennis Sensor isn't the first of its kind -- French racket maker Babolat has one too but it's integrated into the racket itself and sells for around $400.

An attachment-type tennis sensor from California-based Zepp Labs is slightly lighter though with a bulkier mount than Sony's and can store data on up to 2,000 shots in its internal memory. It's priced at $150.

Sony's $200 sensor can attach to some rackets made by Wilson, Prince and Yonex, with other models expected. It stores data on up to 12,000 swings in its internal memory, according to Sony.